Fuel injection system



Oct. 21, 1969 s. G. HlLBoRN 3,473,523

FUEL INJECTION SYSTEM Filed July 12, 1968 3 Sheets-Shes?I 1 ESSheets-Sheet 2 s. G. HILBORN FUEL INJECTION SYSTEM Oct. 2l, 1969 FiledJuly 12, 196s 0d 21, 1959 s. G. HxLBoRN FUEL INJECTION SYSTEM 3Sheets-Sheet 5 Filed July l2. -1968 D ix.:

Ill/4.4141

z rrr w M w r g m vwxh 4 M/ (Km QNN 3,473,523 FUEL LJECTIGN SYSTEMStuart G. Hilborn, South Laguna, Calif., assignor to Fuel injectionEngineering Company, South Laguna, Calif., a corporation of CaliforniaContinuation-in-part of application Ser. No. 545,748, Apr. 27, 1966.This application July 12, 1968, Ser. No. 754,752

lint. Cl. F02m 39/00, 7/00; F0211 J/04 1 U5. Cl. 12S- 1139 ClaimsABSTRACT 0F THE DISCLSURE This application is a continuation-in-part ofapplication Ser. No. 545,748, now abandoned, filed Apr. 27, 1966, Thisinvention relates to a fuel injection system and more particularly to afuel injection system particularly adapted for use with automobileracing engines.

The fuel requirements of an automobile racing engine vary rapidly over awide range. For example, the speed of a supercharged racing engine mayvary from 1000 r.p.m. to over 10,000 r.p.m. in a few seconds. Thethrottle position may change from closed, to fully open, to partly open,and back to fully open within seconds. Each slight variation of throttleposition and of engine speed will produce a corresponding fiuctuation inmanifold pressure which might range, for example, from Zero to 120inches Hg positive boost, then down to 25 inches of Hg vacuum. Theseextreme changes in manifold pressure may occur in just a few seconds asduring an acceleration or drag race in which a racing vehicle mayaccelerate from zero to 200 miles per hour in less than eight seconds.

Each change in engine r.p.rn. or air ow to the engine requires acorresponding and accurately controlled change in fuel ow. lf the fuelinjection system fails to produce these changes or fails to produce themaccurately and without execessive time delay, power is lost, engineperformance is poor, and damage to the engine may occur.

Racing engines must be capable of using a variety of fuels such asgasoline, methanol and nitromethane. When nitromethane is used, therequired fuel flow may be 700% greater than when gasoline is used.Accordingly, it is extremely important that the fuel injection system becapable of quickly altering the fuel-air mixture to accommodate a widevariety of fuels.

Generally, prior art fuel injection systems vary the amount of fuelsupplied to the engine in response to various engine conditions.However, the prior art fuel injection systems are generallyunsatisfactory and not suciently flexible to efficiently operate overthe wide range of fuels, engine r.p.m., and engine air flows required inthe racing engine.

The fuel injection system of this invention quickly and accuratelychanges the rate of fuel ow to the engine in response to a large numberof operating conditions. In particular, excessive richness is avoidedduring deceleration and during periods of very high engine speed. Thefuel injection system can be adapted for different fuels by merelyadjusting a selector valve. All of these features are present duringsupercharged and unsupercharged opnited States Patent 0 rice eration.For supercharged operation auxiliary injection means automaticallysupplies additional fuel to the engine.

The concepts of the present invention can be advantageously embodied ina system which includes a conduit for interconnecting a fuel tank andthe inlet manifold of the engine, a fuel pump for pumping fuel throughthe conduit to the inlet manifold and a metering valve for controllingthe amount of fuel pumped through the conduit to the inlet manifold.Excess fuel or fuel that is supplied by the fuel pump and is notrequired for unsupercharged engine operation or during other phases ofengine operation is returned through various feedback conduits to thefuel tank.

To allow the engine to utilize different fuels or various fuel airmixtures of the same fuel, the fuel injection system accurately controlsthe amount of fuel that is returned to the fuel tank through one of thefeedback conduits. This is preferably accomplished by providing aprimary bypass which includes primary bypass passage means whichprovides a plurality of feedback paths arranged in parallel and aplurality of mixture control valves connected, respectively to theparallel feedback paths. A selector valve is provided for selectivelyallowing fluid to flow through one of the mixture control valves and itsassociated feedback path while blocking fuel ow through the othermixture control valves. Each of the mixture control valves has adifferent size ow orifice therein and hence a different maximum flowrate. Thus, by appropriate 'adjustment of the selector valve differentrates of feedback and different tiow rates of fuel to the engine arerapidly and accurately obtained. The selector valve can be rapidly movedto the desired position so that the fuel-air mixture is quickly andeasily varied a predetermined amount.

The fuel injection system as described above is operable Whether or notthe engine is supercharged. A primary feature of this invention isadapting this fuel injection system for supercharged operation. This maybe accomplished by providing auxiliary injection means, which isresponsive to the pressure in the manifold reaching a predeterminedvalue such as might be caused by supercharging, for supplying at least aportion of the excess fuel from the feedback conduit to the engine.

It is important that the auxiliary injection means be sensitive tofluctuations in supercharger pressure and fuel pressure. Accordingly,the auxiliary injection means includes a return valve in the feedbackconduit for controlling the amount of excess fuel returned to the tankand ya return valve operator which is responsive to the pressures in theinlet manifold and to the fuel pressure in the feedback conduit forcontrolling the opening and closing of the return valve. Moreparticularly, the valve operator in a preferred form includes a housing,a movable diaphragm dividing the housing into first and second chambers,and separate conduits for connecting the rst and second chamber to theinlet manifold and to the feedback conduit, respectively. Thus, thepressure of the fuel in the feedback conduit acts on one side of thediaphragm and the pressure in the inlet manifold acts on the other sideof the diaphragm to control movements of the diaphragm and opening andclosing of the return valve.

In one form of the invention the first chamber, which is connected tothe inlet manifold is Vented to the atmosphere through a small diametervent, and the ow of air from the inlet manifold into the first chamberis controlled by a relatively small diameter jet. By varying the size ofthe Vent opening and/ or the inlet jet, the amount that the return valveis opened in response to a given set of pressure conditions can bevaried. This means that the amount of fuel that is fed through theauxiliary injection system to the engine is likewise variable. Ofcourse, only the fuel that is excess and unneeded for unsuperchargedoperation is fed by the auxiliary injection system to the engine.

In another form of the invention the first chamber is not vented and thejet between the inlet manifold and the first chamber is removed. Thismakes the return valve immediately responsive to changes in manifoldpressure.

In order to obtain an optimum acceleration range, most racing enginesare required to operate at speeds in excess of the speed at which thehorsepower is maximum. As engine speed increases beyond the speed atwhich horsepower is maximum, the total air flow to the engine decreases.However, the output of the fuel pump, which is driven by the engine,continues to increase. Accordingly, the fuel mixture supplied to theengine is excessively rich.

To eliminate this problem, the present invention employs a secondfeedback conduit leading from the discharge side of the fuel pump backto the fuel tank and a high-speed cutoff valve in this conduit. Thehigh-speed cutoff valve, which may be of the relief valve type, is setto start opening at whatever fuel pressure is present in the pump justafter exceeding the speed a which horsepower is maximum. Thus, as theengine speed exceeds the speed at which horsepower is maximum, the fuelpressure increases and the high-speed cutoff valve is automaticallyopened to prevent an increase in fuel liow to the engine. In an actualengine it may be desirable to set this valve to begin opening at a fuelpressure slightly under that which exists when horsepower is maximum to.provide time for the valve to open. Thus, it may be said that the valveshould open at approximately the speed at which horsepower is maximum.To provide smooth opening of the valve, the valve element should beprovided with an orifice defining a leakage path for the fuel.

Another fuel injection problem is presented during deceleration. In thissituation the throttle is suddenly closed and the metering valve issuddenly moved to the idle position. Because the fuel pump is driven bythe engine, the output thereof continues at nearly maximum until theengine speed is reduced. During this period the fuel flow is high andthe engine requirement is low, leaving only the primary bypass throughthe mixture control valves to return the excess fuel to the fuel tank.Under these circumstances the quantity of excess fuel greatly increases.Since the primary bypass will usually not be capable of returning all ofthe excess fuel to the tank under these conditions, the fuel pressurerises and this results in excessive richness of the fuel-air mixture.

The present invention eliminates this problem by providing a secondarybypass passage or feedback passage leading from the metering valve backto the fuel tank, the bypass being automatically opened in response tothe metering valve approaching the idle position. More particularly, themetering valve preferably includes a housing having a flow passagewaytherethrough and a valve element in the low passageway movable between afull open position and an idle position in which the flow passageway isat least partially blocked by the valve element. A passage extendsthrough the valve element and communicates with the secondary bypasspassage. The passage in the valve element is arranged to be blocked bythe housing when the metering valve means is in the full open positionand is in communication with the oW passageway when the valve element isin or near the idle position, the passage in the valve element isexposed to the fuel within the metering valve and at least a portion ofsuch fuel flows through the secondary bypass back to the fuel tank.Thus, excessive richness during deceleration is eliminated. A similarcondition is produced by cars racing from a standing start where a smallthrottle opening and fairly high r.p.m. evists. The secondary bypassprevents excessive richness at this time also.

Fuel is injected into the inlet manifold downstream of the throtle valveby a nozzle which is preferably of the airthe spring gap type. Theair-gap type nozzles are vented to the upstream side of the throttlevalve. The nozzle for injecting fuel fed by the auxiliary injectionsystem are secured to the inlet manifold upstream from the throttlevalve and are not of the air-gap type.

As indicated hereinabove, in one form of the invention, the return valveis not vented to the atmosphere to thereby improve the response of theengine fuel system to changes in manifold pressure. This also helps toprovide a better air-fuel ratio at part throttle. To further improve theairfuel ratio at part throttle, the present invention teaches that thefuel ow to the auxiliary fuel injection nozzle should be a function notonly of inlet manifold pressure but also of metering valve position.This may be accomplished by interconnecting the auxiliary fuel injectionconduit means to the supply conduit downstream of the metering valve.

An engine will operate most efliciently at a given fuelair ratio andfuel flow should be proportional to air ow over a wide range ofoperating conditions. Theoretically, air flow and fuel ow should beproportional to engine r.p.m. In actual practice, however, factors suchas cam shaft timing, manifold pressure, and volumetric efficiency comeinto operation to such an extent that air flow is not proportional tor.p.m., but the fuel pump output is. A significant problem in designinga fuel system, particularly for a racing engine, is to tailor the fuelow rate so that fuel will be proportional to air flow under a wide rangeof operating conditions. Tailoring of a fuel iiow curve for asupercharged engine is particularly diliicult because of the additionalfuel required for supercharged or blown operation. One way to accomplishthis is to use a dual set ot" nozzles, i.e. a main nozzle and anauxiliary nozzle for each cylinder. With this system, the main nozzle issized to provide adequate fuel for unblown operation and the auxiliarynozzle is sized to provide whatever amount ot' additional fuel isrequired for supercharged operation.

According to another embodiment of the present invention, the auxiliarynozzle can be eliminated and the fuel flow curve is accurately tailoredover a wide range of operating conditions. This can be advantageouslyaccomplished with modifier valve means which provides passage means forsupplying fuel to the engine and an openable valve element for providingadditional fuel flow to the engine. In a preferred embodiment, thepassage means includes an orifice in the valve element to therebyprovide a fuel lioW path to the nozzle which remains open regardless ofthe position of the valve element. This orifice is preferably sized toprovide sufiicient fuel for unsupercharged operation and, if desired,for the initial portion of supercharged operation. The valve element isopenable in response to the differential fuel pressure acting thereon toprovide additional fuel flow to the engine. Preferably, the valveelement opens at or shortly after supercharged operation has begun. Thevalve may be of the relief valve type with pressure set to open atwhatever fuel pressure exists when supercharged operation is begun.

The modifier valve can also be used in unsupercharged engines. Here theorifice is sized to provide suicient fuel for idle and for the lowerr.p.m. range and the valve then opens to supply the upper r.p.m. range.The shape of the fuel ow curve can thus be shaped to suit the enginerequirements.

With this embodiment of the present invention, only the main nozzle isrequired and this nozzle must be sized to supply all of the fuel that isrequired for supercharged operation. Thus, the valve element causes asingle nozzle system to function as though it were a dual nozzle systemwhile accurately tailoring fuel supply. Various combinations of springtension of this valve and orifice size iu the primary bypass can beprovided to achieve a fuel flow curve of almost any desired shape. Thus,the maximum horsepower possible can be obtained over a wide range ofengine speeds. As used herein, blown operation or supercharged operationcan be considered to exist when any boost, i.e. pressure increase,occurs, in the inlet manifold of the engine as a result of superchargeroperation.

As the valve element is opened by fuel pressure, it should preferably bepositioned downstream of the pump. The valve is preferably locatedupstream of the metering valve but it could also be located on thedownstream side of the metering valve.

It is normally desirable to enrich the fuel air mixture duringacceleration and for a racing engine, it is important that suchenrichment be promptly obtained. Accordingly, the present inventionprovides a secondary source of fuel under pressure which is responsiveto opening of the throttle to provide additional fuel for acceleration.

To accomplish this, the present invention provides an accelerationchamber in communication with a location in the fuel supply conduit sothat when the engine is operating at part throttle and the fuel pressureis relatively high, the acceleration chamber is filled or partiallyfilled with fuel from the system. When the throttle is opened toaccelerate the engine, the fuel pressure drops and this tends to drawfuel out of the acceleration chamber to provide momentary enrichment. Byproviding a suitably sized orifice in the conduit between theacceleration chamber and the fuel supply conduit, the rate and durationof fuel ow out of the acceleration chamber can be adjusted.

lt is important that the acceleration chamber be connected into the fuelsupply conduit at a location therein which is upstream of the meteringvalve. If such location were downstream the metering valve, the pressureat such location would be reduced when the metering valve closes andthus, the fuel in the acceleration chamber would drain into the engineduring a part throttle condition.

Of course, in order that the acceleration chamber will be supplied withfuel under pressure, it should be located downstream of the pump.Furthermore, if a valve of the type described above is utilized in lieuof an auxiliary injection nozzle, the acceleration chamber shouldpreferably be connected to the fuel supply conduit downstream thereof.lf the acceleration were connected to the fuel supply conduit upstreamof this valve, the fuel pressure would bleed olf through the primarybypass during a part throttle condition. Even if such bleed off did notoccur, the fuel would encounter additional resistance in passing throughthe valve.

The invention, both as to its organization and method of operation,together with further features and advantages thereof, may best beunderstood by reference to the following description taken in connectionwith the accompanying drawing in which:

FIG. l is a diagrammatic illustration of one form of a fuel injectionsystem constructed in accordance with the teachings of this inventionwith many of the components thereof being shown in longitudinal section;

FIGS. 2a and 2b are enlarged fragmentary sectional views taken alongline 2-2 in FIG. l and illustrating the idle position and the full openposition, respectively, of the metering valve; and

FIG. 3 is a fragmentary view partially in section illustrating amodified high-speed cutoff valve.

FIG. 4 is a diagrammatic view partially in section of a second form offuel injection system constructed in accordance with the teachings ofthis invention.

FIG. 5 is a diagrammatic illustration of a third form of fuel injectionsystem consuucted in accordance with the teachings of this inventionwith many of the components thereof being shown in longitudinal section.

FIG. 6 is a fragmentary diagrammatic view partially in section of afourth form of fuel injection system constructed in accordance with theteachings of this invention.

Referring to the drawing and in particular FIG. 1 thereof, a conduit 11interconnects a fuel tank 13 and an inlet manifold 15 of an engine (notshown). The engine is of the internal combustion type and one of theinlet manifolds 15 is provided for each of the several cylinders of theengine. The inlet manifold 15 has a throttle valve 17 therein which iscontrolled in the conventional manner.

A fuel pump 19, which is driven by the engine draws fuel from the tank13 and pumps it through the conduit 11, a fuel filter 21, a meteringvalve 23, and an injector nozzle 25, which is preferably of the air-gaptype to the inlet manifold 15. The injector nozzle 25 injects fuel intothe inlet manifold 15 downstream of the throttle valve 17.

To permit the engine to burn various fuels and to permit a variation infuel-air mixture, a primary bypass is provided for returning the excessfuel supplied by the fuel pump 19. The primary bypass includes a primarybypass conduit or feedback conduit 27 that interconnects the dischargeside of the fuel pump 19 and the fuel tank 13. The primary bypassconduit 27 provides a plurality of parallel passageways 29, 31, 33having mixture control valves 35, 37 and 39, respectively, therein. Aselector valve 41 in the primary bypass conduit 27 selectively allowsfuel to ow through one of the mixture control valves while blocking fuelflow from the conduit 27 to the tank 13 through the other of the mixturecontrol valves. In the position illustrated, fuel can flow through theselector valve 41 and the mixture control 39, but cannot flow throughthe mixture control valves 35 and 37.

Each of the mixture control valves includes a body portion 43, a tubularnut portion 45 secured to the body portion, a valve element 47 springbiased to the closed position, and a ow control jet 49 retained in thenut portion. Because the valve elements 47 are spring biased, themixture control valves function as check valves to prevent backflowtoward the fuel pump. The maximum quantity of fuel that the mixturecontrol valves can pass depends upon the size of the jet 49. The size ofthe openings through the jets 49 of the mixture control valves 35, 37and 39 progressively increases so that the mixture control valve 39 willreturn a larger quantity of fuel to the tank 13 than the mixture controlvalve 35 and will accordingly provide a relatively lean fuel-air mixtureto the engine. lf a richer fuel-air mixture is desired, the selectorvalve 41 can be quickly and easily rotated to allow ow through either ofthe valves 35 and 37. Any suitable number of mixture control valves maybe provided.

During deceleration, the throttle valve 17 is closed and the meteringvalve 23 is in the idle position. The fuel pump 19, Which is driven bythe engine, continues to pump fuel at a relatively high rate until theengine speed is reduced, thereby producing an excessive amount of fuel,only some of which can be returned to the tank 13 through the primarybypass. To return the remainder of the excess fuel, a secondary bypassconduit or feedback conduit 51 is provided for interconnecting themetering valve 23 with the conduit 27.

The metering valve 23 includes a housing 53 having a iiow passageway 55extending therethrough and a cylindrical eccentrically mounted valveelement 57 mounted in the passageway. The valve element 57 is mountedfor rotation about an axis which is generally transverse thelongitudinal axis of the flow passageway 55. The valve element 57 isrotatable between a full open position (FIG. 2b) and an idle position(FIG. 2a). The valve element 57 has a passage 59 which communicates withthe secondary bypass conduit 51 through a port 61 iu the housing 53. Thepassage 59 has an inlet section 63 which is closed by the housing 53when the valve is rin the full open position (FIG. 2b) and is exposedwithin the flow passageway 55 when the valve is in the idle position(FIG. 2a). The inlet section l63 is arranged within the valve element 57to be exposed within the ow passage- Way as the valve element is rotatedfrom the full open position toward the idle position. Thus, as the idleposition is approached during deceleration the excess fuel supplied bythe fuel pump 19 is returned through the secondary bypass conduit 51 andthe conduit 27 to the fuel tank 13.

To maintain a minimum fuel pressure for idling operation of the engine,a check valve 65, which `is operable at such minimum pressure isprovided in the conduit 51. j

The check valve y is similar in construction to the valve 35 andincludes a body portion 67, a tubular nut portion 69 threadedly receivedwithin the body portion, a valve element 71, and a spring 73 urging thevalve element 71 to the closed position. The force of the spring 73 isselected to maintain a certain minimum fuel pressure in the conduit 11for idling.

As explained hereinabove, operation of a racing engine at speeds inexcess of the speeds at which the horsepower is maximum causes the fuelmixture to be excessively rich. To obviate this problem, a high-speedcutoff valve 75 is connected at its inlet end to the discharge side ofthe fuel pump 19 and at its outlet end to a feedback conduit 77 whichleads directly to the fuel tank 13. The relief valve, which is usuallyprovided on fuel pumps, is not required on the fuel pump 19. The valve75 includes a body portion 79, a tubular threaded portion 81 threadedlyreceived within the body portion, a movable valve element 83, a spring85 urging the valve element to the closed position, and a tubular spacer87 against which the spring y85 bears. The force exerted by the spring85 is set so that the valve 75 will open at whatever fuel pressureexists when the speed at which horsepower is maximum is exceeded. Thevalve 75 limits fuel ow to the engine to the amount utilized by theengine when it is producing its maximum horsepower.

FIG. 3 illustrates a valve 89 of alternate construction which may beused in lieu of the valve 75. The valve 89 is identical to the valve 75except for the addition of an O-ring 91 formed in a groove in the valveelement and the addition of Washers 93 behind the tubular spacer 87 foradjusting the force supplied by the spring 85 to the valve element.

The fuel injection system which has been described in detail thus far isusable with or without supercharging of the engine. An important featureof this invention is the provision of auxiliary injection means which isresponsive to supercharging of the engine for supplying at least aportion of the excess fuel from the feedback conduits 27 and 51 to theengine. The auxiliary injection means includes a return valve 95 forcontrolling the amount of excess fuel returned to the tank 13, a conduit97, a check valve 99, a junction block 101, and an auxiliary injectornozzle 103 secured to the inlet manifold 15 upstream of the throttlevalve 17.

T'he return valve 95 includes two housing sections 105 and 107 securedtogether by threaded fasteners 109 to form a valve housing. A movableflexible diaphragm 111 is clamped between the housing sections and 107to divide the valve housing into a control chamber 113 and a fuelchamber 115. The housing section 107 defines an annular valve seat 117,an inlet 119 and an outlet 121. The diaphragm 111 carries a valveelement 123 therewith which is operative to open and close a valvepassageway 124 extending between the inlet 119 and the outlet 121. Thecontrol chamber 113 is connected to the inlet manifold 15 downstream ofthe supercharger and either upstream or downstream of the throttle valveby a pressure-sensing conduit 125 and a small diameter jet 127. Thecontrol chamber 113 is vented to the atmosphere through an outlet jet129 and a vent 131.

The check valve 99 may be identical to the valve 75 and will require acertain minimum fuel pressure to open. 'Ihe junction block 101 serves asa plenum chamber for supplying fuel to the auxiliary injectors 103, oneof which is located in each of the inlet manifolds 15.

When the pressure in the inlet manifold is atmospheric or below, theexcess fuel in the conduit 27 will force the diaphragm 111 and the valveelement 123 upwardly to open the return valve 95 and allow all of theexcess fuel to return to the tank 13. When the pressure lin the inletmanuifold increases, as when the supercharger is operating, the pressureon the upper side of the diaphragm 111 is suflicient to prevent or limitopening of the valve 95, in which case the excess fuel Hows through theconduit 97, the .check valve 99, the junction block 101, and theauxiliary injectors 103 to the inlet manifolds 15. Should superchargingof the engine be discontinued, the return valve 95 would automaticallyopen to allow the excess fuel to be returned to the tank 31. Theauxiliary injection system only uses fuel that the primary injectionsystem, i.e., the system feeding the nozzles 25, has declared to beexcess. Thus, only the excess fuel is supplied to the inlet manifold bythe auxiliary injection system. The proportions of the excess fuel thatare returned to the tank 13 and that are supplied to the injectors 103may be varied by varying the size of the jets 127 and 129.

It is preferred that the nozzle 25 be of the air-gap type illustrated.The nozzle 25 includes a body 133 having an axial bore and an axialcounterbore 137 therein. The body 133 is threadedly connected to theinlet manifold 15 and the counterbore 137 is placed in communicationwith and receives air from the upstream side of the throttle valve 17 bya plurality of ports 139 in the body 133 and a passageway 141 in theinlet manifold 15. Thus, the air gap nozzle receives air from theupstream side of the throttle 17 when the throttle is closing or closed.

FIG. 4 shows a second embodiment of the invention which produces abetter fuel-air ratio at part throttle and improves throttle response.The embodiment of FIG. 4 s identical to the embodiment of FIG. 1 exceptas specilically noted herein and corresponding parts are designated bycorresponding reference characters followed by the letter a.

The embodiment of FIG. 4 has primary bypass means, secondary bypassmeans, and high-speed cutoff means which are identical to thecorresponding portions described in connection with FIG. l. FIG. 4differs from FIG. l in that the return valve 95a thereof is not ventedto atmosphere and the conduit 125a leading to the manifold 15a upstreamfrom the throttle valve 17a does not have a jet or orifice I127 therein.With this arrangement, the valve 95a is immediately responsive topressure changes in the manifold 15a upstream from the throttle valve17a such as may be caused by the supercharger. This tends to improve theresponse of the fuel control system to changes in the manifold pressure.

The second difference between the systems of FIGS. l and 4 is that withthe latter, the auxiliary injection nozzle 103a is supplied with fuelfrom a conduit 97a which is connected to the supply conduit 11adownstream from the valve element 57a of the metering valve 23a. ln theembodiment illustrated in FIG. 4, the conduit 97a is3connected to thehousing 53a of the metering valve 2 a.

With this arrangement, the manifold pressure 125a affects fuel flow tothe auxiliary nozzle 103a in that it influences the amount of fuel thatcan return to the fuel tank 13a through the bypasses 51a and 27a. `Inaddition, the position of the valve element 57a of the metering valve23a controls the amount of fuel fed to the auxiliary injection nozzle103:1. With this arrangement the fuel which passes through the meteringvalve 23a is divided between the nozzles 103a and 25a in accordance withrelatively fixed percentages. This construction results in improvedacceleration and throttle response and a better fuel air-ratio at partthrottle.

FIG. 5 illustrates a third embodiment of the present invention which isidentical to the embodiment of FIG.

4 in every respect not specifically set forth herein. Protions of thefuel system of FIG. 5 corresponding to portions of the systems of FIGS.l and 4 are designated by corresponding reference numbers followed bythe letter b.

The embodiment of FIG. 5 differs from the embodiment of FiG. 4 in thatthe former has no auxiliary injection nozzle and is provided with amodifier valve 161 which has no counterpart in the embodiments of FIGS.l and 4. The valve 161 includes housing sections 163 and 165 which arethreadedly attached and which define a valve body having a flowpassageway therethrough. The valve body defines a valve seat 166. Thevalve 161 also includes a valve element 167 movable axially between aclosed position in which the valve element tightly engages the valveseat 166 and an open position in which the valve element is spacedaxially from the valve seat to permit fuel flow therebetween. A spring169 is provided for urging the valve element toward the closed positionthereof and one or more spacers or washers 173 may be provided asdesired for the purpose of varying the force exerted by the spring onthe valve element. The valve element 167 has a small diameter fixed areaorifice 175 extending through a central region thereof through whichfuel can fiow regardless of the position of the valve element.

In operation of the system shown in FIG. 5, the spring 169 normallyretains the valve element 167 in the closed position thereof duringunsupercharged operation of the engine. During this time fuel issupplied through the orifice 175 and the metering valve 23h to the fuelinjection nozzle 2511. During this time, the fuel pressure acting on theleft-hand face of the valve element 167 is insuflicient to overcome thebiasing force of the spring 169 and of the fuel pressure on theright-hand face of the valve element.

As engine speed increases it drives the fuel pump and the superchargerfaster. Thus, the fuel pressure on the discharge side of the fuel pumpand the air pressure provided by the supercharger increase in accordancewith a predetermined relationship. The force exerted by the spring 169is preferably selected so that the fuel pressure on the left-hand faceof the valve element 167 will be just enough to lift the Avalve elementoff of the seat 166 at approximately the time that the supercharger iseffective to produce any boost, i.e. pressure increases, in the manifoldas a result of supercharger operation. If desired, however, the element167 may be maintained on the valve seat 166 for the first portion ofsupercharged operation. Thus, it may be stated that the valve y167preferably opens at approximately the instant that there is somepressure increase in the manifold as a result of supercharge operation.

The valve element 167 is lifted off of the seat 166 in an appropriaterelationship to the increase of air supplied by the supercharger. Byvarying the spring tension, the size of the orifice 175, and the amountof fuel bypassed through the primary bypass 2719, a fuel flow curve ofalmost any shape can be produced. This enables the production of maximumhorsepower in both `the high and low speed ranges and also eliminatesthe need for the auxiliary injection nozzle. Of course, it is necessarythat the main fuel nozzle 2Sb be sized so that they can supply all ofthe fuel required by the engine for supercharged operation.

Another difference between the embodiment of FIG. 5 and the embodimentsof FIGS. l-4 is that the high speed cutoff valve 75h has a valve element83h in which a small diameter orifice 177 has been formed. With thisconstruction, the high speed cutoff valve 75h is continuously operativeto feed back a very small quantity of fuel. This causes the valveelement 831; to open gradually and smoothly as the fuel pressureincreases. It should be understood that the high speed cutoff valve ofany of the embodiments of the invention described herein may be providedwith an orifice in the valve element thereof such as the orifice 177.When the high speed cutoff valve 75h is provided with the orifice 177,the high speed cutoff valve is preferably located on the upstream sideof the metering valve to avoid back flow into the fuel line at -partthrottle.

FIG. 6 shows still another embodiment of the present invention which isidentical to the embodiment shown in FIG. 5 except for the presence ofan acceleration chamber 179. Portions of the embodiment `of FIG. 6corresponding to the embodiment of FIG. 5 are designated bycorresponding reference characters followed by the letter c. Theacceleration chamber 179 in the embodiment illustrated is in the form ofa tank or container. Communication between the fuel supply conduit 11Cand the acceleration chamber 179 is provided by an interconnectingconduit 181 which is connected to the conduit 11C intermediate themodifier valve 161e and the metering Valve 23C. Fuel can flow throughthe conduit 181 in either direction between the conduit 11C and theacceleration chamber 179. A fixed area orifice 183 is provided at anysuitable location in the conduit 181.

At part throttle, the metering valve 23C is at least partially closed sothat the pressure of the fuel in the line 11a` will ordinarily besufficiently high to cause flow of fuel through the conduit 181 and theorifice 183 into the acceleration chamber 179. The acceleration chamber179 is a closed chamber and as fuel is fed therein, the air in thechamber is compressed. When the throttle and metering valve 23C areopened to accelerate the engine, the pressure in the line 11a upstreamof the metering valve 23C and downstream of the modifier valve 161Cdrops sufficiently so that there is a pressure differential between thispoint and the fuel within the acceleration chamber 179. Accordingly, thecompressed air in the chamber 179 forces the fuel in the accelerationchamber through the orifice 183, the conduit 181 and the metering valve23C to the engine. The rate and duration of fuel fiow out of the chamber179 can be controlled by appropriately sizing of the orifice 183. Thus,the fuel in the acceleration chamber 179 forms, in effect, a secondarysupply of fuel under pressure which is automatically utilized inresponse to opening of the throttle.

It will be appreciated that if the line 181 would be joined to thecondiut 11c `downstream of the metering valve 23C, that closing of themetering valve might very well result in a low pressure conditiondownstream thereof which would cause drainage of the fuel in theacceleration chamber into the engine. For this reason, the conduit 181should be joined to the conduit 11C upstream of the metering valve 23C.Similarly, if the conduit 181 would be joined to the conduit 11cupstream of the modifier valve 161C, the fuel in the accelerationchamber might bleed off toward the pump and even if this did not occur,the fuel would have to overcome the resistance afforded by the valve161C. Accordingly, the location of the union between the conduits 11e`and 181 illustrated in FIG. 6 is preferred. The acceleration chamber 179shown in FIG. 6 can be utilized with any of the embodiments of theinvention described herein.

Although exemplary embodiments of the invention have been shown anddescribed, many changes, modifications, and substitutions may be made byone having ordinary skill in the art without necessarily departing fromthe spirit and scope of this invention.

I claim:

1. In a fuel injection system for supplying fuel from a tank to anengine wherein the engine has a supercharger and an inlet manifold forsupplying air thereto, the combination of:

a first fuel injection nozzle for injecting fuel into the engine;

supply conduit means for interconnecting the tank and said first fuelinjection nozzle;

a fuel pump for pumping fuel from the tank through 'l i. said supplyconduit means and the first fuel injection nozzle; metering Valve meansfor controlling the amount of fuel pumped through said supply conduitmeans to said first fuel injection nozzle, said metering valve meanshaving an idle position in which only a small quantity of fuel issupplied to the first fuel injection nozzle and a full open position inwhich a greater quantity of fuel is fed to the first fuel injectionnozzle;

feedback conduit means for returning at least a portion of an excessfuel pumped by said fuel pump from said supply conduit means to alocation on the intake side of said pump;

an auxiliary fuel injeciton nozzle for injecting fuel into the engine;an auxiliary injection conduit means leading from a location in saidfeedback conduit means to said auxiliary fuel injection nozzle to supplyfuel thereto; and

valve means in at least one of said auxiliary injection conduit and saidfeedback conduit responsive to the pressure in the inlet manifoldreaching a predetermined value for supplying at least a portion of theexcess fuel from said feedback conduit means through said auxiliaryinjection conduit means to said auxiliary fuel injection nozzle.

2. A combination as defined in claim 1 wherein said valve means isresponsive to operation of the supercharger to supply fuel to saidauxiliary injection nozzle.

3. In a fuel injection system for supplying fuel from a tank to an inletmanifold of an engine, the combination of:

conduit means for interconnecting the tank and the inlet manifold;

a fuel pump for pumping fuel through said conduit means from the tank tothe inlet manifold;

means for driving the fuel pump at a speed which increases with anincrease in engine speed whereby the rate of fuel pumped by the fuelpump increases with engine speed;

metering valve means for controlling the amount of fuel pumped throughsaid conduit means to said inlet manifold;

feedback conduit means providing a passageway for returning at least aportion of any excess fuel supplied by said pump to a location on theintake side of the pump; and

a high-speed cutoff valve including a valve element movable between anopen position in which fuel can flow through said cut-off valve andthrough the feedback conduit means to said location and a closedposition in which no more than a relatively small quantity of fuel canflow through said cut-off valve, said valve element being movable tosaid open position in response to the engine exceeding approximately thespeed at `which horsepower is maximum for causing at least some of theexcess fuel to return through said feedback conduit means at a ratewhich increases to pump delivery pressure.

4. A combination as defined in claim 3 wherein the fuel pressuredownstream from said pump varies with increasing engine speed and saidvalve means is responsive to the fuel pressure existing just beyond thepoint where engine horsepower is maximum to cause sufficient quantitiesof the fuel to return through said feedback conduit means to prevent anincrease in fuel flow to the engine.

5. A combination as defined in claim 3 including primary bypass passagemeans for returning a portion of the fuel supplied by said pump to theintake side of said fuel pump and adjustable means in said primarybypass passage means for controlling the rate of flow of fueltherethrough to thereby permit adjustment of the fuel air ratio.

6. A combination as defined in claim 3 including secondary bypasspassage means leading from said supply i2 conduit means on the dischargeside of said fuel pump to a region in said system on the intake side ofsaid fuel pump and means responsive to the metering valve means reducingthe amount of fuel pumped through the metering valve means to said inletmanifold for increasing the maximum flow rate which can occur throughsaid secondary bypass passage means.

7. A combination as defined in claim 3 `wherein said valve meansincludes a valve element movable between open and closed positions tocontrol the ow of fuel through said feedback conduit means, said valveelement having a port therein through which small quantities of fuel caniow independently of the position of said valve element.

8. In a fuel injection system for supplying fuel from a tank to an inletmanifold of an engine, the combination of:

conduit means for interconnecting the tank and the inlet manifold;

a fuel pump for pumping fuel through said conduit means from the tank tothe inlet manifold;

means for driving the fuel pump at a speed which ncreases with anincrease in engine speed whereby the rate of fuel pumped by the fuelpump increases with engine speed;

metering valve means for controlling the amount or fuel pumped throughsaid conduit means to said inlet manifold;

feedback conduit means providing a passageway for returning at least aportion of any excess fuel supplied by said pump to a location on theintake side of the pump;

valve means in said feedback conduit means for controlling the flow offuel therethrough to the intake side of said pump; and

said valve means including a valve body defining a flow passagewaytherethrough with said flow passageway forming a portion of saidfeedback conduit means` a valve element movable in said flow passagewaybetween an open position in which a substantial quantity of fuel canflow through said flow passageway and a closed position, and biasingmeans for urging said valve element toward said closed position, saidvalve element being movable to the open position against the force ofsaid biasing means in response to the engine exceeding approximately thespeed at which horsepower is maximum whereby at least some of the excessfuel can return through said ow passageway.

9. A combination as dened in claim S wherein said valve means includesleakage passge means for permitting some of the fuel to return throughsaid feedback conduit means when said valve element is in said closedposition.

10. In a fuel injection system for supplying fuel from a tank to aninlet manifold of an engine, the combination of:

conduit means for interconnecting the tank and the inlet manifold;

a fuel pump for pumping fuel through said conduit means from the tank tothe inlet manifold;

a metering valve for controlling the amount of fuel pumped through saidconduit means to the inlet manifold, said metering valve having a fullopen position in which maximum fuel flow to the inlet manifold may occurand an idle position in which a substantially lesser amount of fuel canflow through said metering valve to the inlet manifold;

bypass passage means for returning at least some of any excess fuelsupplied by said pump from said conduit means to a location on theintake side of' said pump; and

said metering valve including a valve housing having a flow passagewaytherethrough, a movable valve element in said ow passageway movablebetween a full open position in which said iiow passageway is open andan idle position in which said flow passageway is at least partiallyblocked by said valve element, passage means extending through saidvalve element and communicating with said bypass passage means, meansfor blocking said passage means when said metering valve is in said fullopen position, said passage means communicating with said flowpassageway when said valve element is in said idle position.

11. ln a fuel injection system for supplying fuel from a tank to anengine wherein the engine has a supercharger and an inlet manifold witha throttle valve therein downstream of the supercharger, the combinationof:

nozzle means for injecting fuel into the inlet manifold downstream ofthe throttle valve;

supply conduit means for interconnecting the tank and said nozzle means;

a fuel pump for pumping fuel from the tank through said supply conduitmeans and the nozzle means to the inlet manifold, said fuel pump beingdriven in synchronism with the engine;

a metering valve for controlling the amount of uid pumped through saidsupply conduit means to said nozzle means;

a bypass for returning some of the fuel pumped by the pump to a locationon the intake side of said pump;

selective metering means in said bypass to control the amount of fuelpasisng through said bypass; and

means responsive to a predetermined positive pressure in said manifoldupstream from the throttle valve to bleed fuel from the bypassdownstream from said selective metering means into said inlet manifoldto augment the fuel delivery to the inlet manifold.

l2. In a fuel injection system for supplying fuel from a tank to aninlet manifold of an engine, the combination of:

conduit means for interconnecting the tank and the inlet manifold;

a fuel pump for pumping fuel through said conduit means from the tank tothe inlet manifold;

metering valve means for controlling the amount of fuel pumped `throughsaid conduit means to said inlet manifold;

feedback conduit means providing a plurality of parallel fuelpassageways for returning any excess fuel supplied by the pump from saidconduit means to a location or the intake side of the fuel pump;

each of said passageways having a mixture control valve therein forcontrolling the amount of fuel flow through its respective passageway,each of said mixture control valves having a different maximum ow rateto thereby provide different flow rates through each of saidpassageways; and

selector valve means for selectively allowing `fuel to flow through oneof said mixture control valves while blocking fuel ow from said conduitmeans to the tank through the other of said mixture control Valveswhereby the amount of fuel returning through said feedback conduit meanscan be rapidly changed.

13. A combination as defined in claim 12 wherein each of said mixturecontrol valves includes a valve element, biasing means for urging thevalve element toward a closed position and a fixed 'area orifice forcontrolling the maximum ow rate through such mixture control valve. 14.A combination as defined in claim 12 including a return valve in saidfeedback conduit means responsive to manifold pressure for providingadditional control of the fuel flowing through the feedback conduitmeans.

l5. ln a fuel injection system for supplying fuel to an engine, thecombination of:

nozzle means for injecting fuel into the engine;

supply conduit menas for supplying fuel to the nozzle means;

a fuel pump for pumping fuel through said supply conduit means to thenozzle means;

a metering valve for controlling the amount of fuel pumped through saidsupply conduit means to said nozzle means, said metering valve having afull open position in which maximum fuel ow therethrough may occur andan idle position in which a substantially lesser rate of fuel flowthrough the metering Valve can occur;

primary bypass passage means leading from said supply conduit means onthe discharge side of said fuel pump to a location in said system on theintake side of said fuel pump;

adjustable means in said primary bypass passage means for controllingthe rate of flow of fuel therethrough to thereby permit adjustment ofthe fuel-air ratio;

secondary bypass passage means leading from said supply conduit means onthe discharge side of said fuel pump to a region in such system on theintake side of said fuel pump; and

means responsive to said metering valve being in said full open positionfor at least substantially minimizing the maximum ow rate which canoccur through said secondary bypass passage means and responsive to themetering valve being in said idle position for increasing the maximumflow rate which can occur through said secondary bypass passage means.

16. A combination as defined in claim 15 including return valve means,said primary and secondary bypass passage means leading to said returnvalve means, said return valve means being responsive to manifoldpressure for exerting a control influence on the fuel flow through saidprimary bypass passage means.

17. A combination as defined in claim 15 wherein the rate of fuel flowpumped by said fuel pump increases with engine speed and including ahigh speed cutoff bypass passage means and high speed cutoff valve meansresponsive to engine speed exceeding approximately the speed at whichhorsepower is maximum for permitting at least some of the excess fuel toreturn through said high speed cutoff bypass passage means.

18. In a fuel injection system for supplying fuel from a tank to anengine wherein the engine has an inlet manifold for supplying airthereto, the combination of a first fuel injection nozzle for injectingfuel into the engine;

supply conduit means for interconnecting the tank and said first fuelinjection nozzle;

a fuel pump for pumping fuel from the tank through said supply conduitmeans and the first fuel injection nozzle;

metering valve means having a movable valve element for controlling theamount of fuel pumped through said supply conduit means to said firstfuel injection nozzle, said metering valve means having an idle positionin which only a small quantity of fuel is supplied to the first fuelinjection nozzle and a full open position in which a greater quantity offuel is fed to the first fuel injection nozzle;

a region of said supply conduit means lying intermediate said valveelement and the inlet manifold;

feedback conduit means for returning at least a portion of any excessfuel pumped by said fuel pump from said supply conduit means to alocation on the intake side of said pump;

an auxiliary fuel injection nozzle for injecting fuel into the engine;

an auxiliary injection conduit means leading from at least one of saidfeedback conduit means and said region of said supply conduit means tosaid auxiliary fuel injection nozzle to supply fuel thereto; and

valve means in at least one of said auxiliary injection conduit meansand said feedback conduit responsive to the pressure in the inletmanifold for supplying at least a portion of the excess fuel from saidfeedback conduit means through said auxiliary injection conduit means tosaid auxiliary fuel injection nozzle.

19. A combination as defined in claim 18 wherein said valve means isresponsive to air pressure in the inlet manifold and fuel pressure inthe feedback conduit means and includes a housing, a movable diaphragmdividing said housing into first and second chambers, means forconnecting said first chamber to said inlet manifold, means forconnecting said second chamber to said feedback conduit means to therebycause movement of said diaphragm in response to predetermined variationsin air pressure in the inlet manifold and fuel pressure in the feedbackconduit means, and means for causing opening and closing of said valvemeans in response to movement of said diaphragm.

20. A combination as defined in claim 18 wherein said feedback conduitmeans includes a plurality of mixture control valves connected inparallel and selector valve means for selectively allowing fluid to flowthrough one of said mixture control valves while blocking fuel flow fromsaid conduit means to the tank through the other of said mixture controlvalves, each of said mixture control valves having a different maximumflow rate whereby the feedback rate can be adjusted to compensate fordifferent fuels.

21. A combination as defined in claim 18 wherein said feedback conduitmeans includes high-speed cutoff valve means responsive to the enginespeed exceeding the speed at which horsepower is maximum for returningat least some of the excess fuel to a location on the intake side ofsaid pump.

22. A combination as defined in claim 18 wherein said feedback conduitmeans includes secondary bypass means responsive to said metering valvemeans approaching said idle position for returning at least some of theexcess fuel to a location on the intake side of said pump.

23. A combination as defined in claim 18 wherein the inlet manifold hasa throttle valve therein, said first injection nozzle being secured tothe inlet manifold downstream of the throttle valve and means areprovided for providing communication between a location within saidfirst injection nozzle and said inlet manifold upstream of the throttlevalve regardless of the position of the throttle valve.

24. A combination as defined in claim 18 wherein said feedback conduitmeans includes primary bypass means for feeding back selectivelyvariable quantities of excess fuel to a location on the intake side ofsaid pump, highspeed cutoff valve means responsive to the engine speedexceeding the speed at which horsepower is maximum for feeding back atleast some of the excess fuel, and secondary -bypass means responsive tothe metering valve means approaching said idle position for feeding backat least a portion of the excess fuel.

25. A combination as defined in claim 18 wherein the inlet manifold hasa throttle valve and said first injection nozzle and said auxiliaryinjection nozzle are positioned on the downstream and upstream sides,respectively, of said throttle valve.

26. A combination as defined in claim 18 wherein said auxiliaryinjection conduit means leads from said region to the auxiliary fuelinjection nozzle whereby the fuel flow through said auxiliary injectionconduit means is a function of metering valve position and inletmanifold pressure.

27. In a fuel injection system for supplying fuel to an engine, thecombination of:

a nozzle for injecting fuel into the engine;

supply conduit means for supplying fuel to the nozzle;

a fuel pump for pumping fuel through said supply conduit means and thenozzle to the engine, said fuel pump being driven by the engine so thatthe pressure of the fuel pumped thereby increases with engine speed;

a metering valve for controlling the amount of uid pumped through saidsupply conduit means to said nozzle;

bypass means for bypassing some of the fuel pumpen by the pump;

valve means arranged in series with said metering valve in said supplyconduit means on the discharge side of said fuel pump responsive to apredetermined pressure condition in said supply conduit means foropening to permit said fuel to supply fuel :o said nozzle through saidsupply conduit means; and

means defining a fuel ow passage for supplying fuel from the fuel pumpto said nozzle independently or said valve means and said predeterminedpressure condition whereby the opening of said valve means providesadditional fuel to the nozzle to thereby tailor the fuel flow to saidnozzle.

28. A combination as defined in claim 27 including means responsive toopening the throttle of the engine for supplying additional quantitiesof fuel to said supply conduit means at a location therein downstreamfrom sald valve means.

29. In a fuel injection system for supplying fuel to an engine, thecombination of:

nozzle means for injecting fuel into the engine;

supply conduit means for supplying fuel to the nozzle means;

a fuel pump for pumping fuel through said supply conduit means and thenozzle means to the engine:

a metering Valve for controlling the amount of fuel pumpedthrough saidsupply conduit means to said nozzle means;

valve means in said supply conduit means for providing additionalcontrol of the fuel iiow through said supply conduit means to the nozzlemeans;

said valve means including a valve body having a flow passagewaytherethrough, a movable valve element in said valve body for controllingfuel ow through said flow passageway in which said iiow passageway isopen to permit fuel flow therethrough and a closed position in whichsaid valve element .at least partially blocks fuel fiow through saidflow passageway and means for urging said valve element toward theclosed position, said valve element being movable toward the openposition in response to predetermined engine operating conditions topermit fuel to iiow therethrough and through said supply conduit meansto said nozzle means to tailor the fuel iiow to the engine.

30. A combination as defined in claim 29 wherein said means for urgingincludes resilient means and said means defining a fuel ow passageincludes an orifice in said valve element.

31. In a fuel injection system for supplying fuel to an engine whereinthe engine has a supercharger, the combination of:

nozzle means for injecting fuel into the engine, said nozzle means beingof sufficient size to permit it to supply the maximum fuel ow raterequired by the engine for supercharged operation;

supply conduit means for supplying fuel to the nozzle means at saidmaximum flow rate;

a fuel pump for pumping fuel through said supply conduit means and thenozzle means to the engine` said fuel pump being driven by the engine sothat the pressure of the fuel pump thereby increases with engine speed;

a metering valve -for controlling the amount of fuel pumped through saidsupply conduit means to said nozzle means;

valve means in said supply conduit means forproviding additional controlof the fuel flow to the nozzle means;

said valve means including a valve body having a flow passagewaytherethrough of sufficient size to supply fuel at said maximum fuel flowrate, a valve element movably mounted in said ow passageway forcontrolling fuel flow therethrough, and a valve seat, said valve elementbeing movable in said flow passageway between a closed position in whichsaid valve element engages said valve seat and an open position in whichsaid valve element is spaced at least in part from said valve seat topermit flow through said iiow passageway, said valve means alsoincluding biasing means for urging said valve element toward the closedposition; and

said valve element having an apperture therethrough to permit continuoussupply of fuel to said nozzle means when said valve element is in saidclosed position thereof, said aperture being sized to provide sufiicientfuel for a first range of engine operation which amount of fuel is lessthan said maximum fuel flow rate, said valve element being openable inresponse to predetermined pressure conditions in said supply conduitmeans to permit supply of said maximum fuel ow rate through said flowpassageway.

32. A combination as defined in claim 31 wherein said valve means islocated downstream of the fuel pump and upstream of said metering valve,the combination also including means defining an acceleration chamber,said acceleration chamber being in communication with a location in saidsupply conduit means intermediate said valve means and said meteringvalve whereby fuel can be supplied to said -chamber from said supplyconduit means and said chamber can supply fuel to said supply conduitmeans depending upon the differential pressure between said chamber andsaid location.

33. In a fuel injection system for supplying fuel to an engine, thecombination of:

supply conduit means for supplying fuel to the engine;

a -fuel pump for pumping fuel through said supply conduit means to theengine;

a metering valve for controlling the amount of fuel pumped through saidsupply conduit means to said nozzle means;

an acceleration chamber for containing a compressible uid; and

interconnecting conduit means for providing a fiuid flow path between alocation in said supply conduit means upstream of said metering valveand downstream of said pump to permit the supply of fuel to saidacceleration chamber when the fuel pressure at said location of saidconduit means is relatively high, the supply of fuel to saidacceleration chamber compressing said compressible uid to thereby createa secondary fuel source'under pressure whereby opening of the meteringvalve creates a relatively low pressure condition at said location insaid supply conduit means to thereby permit the secondary fuel source tosupply fuel to said supply conduit means.

34. A combination as defined in claim 33 including means in saidinterconnecting conduit means for restricting said fiow passageway tothereby provide some Control of the fuel flow therethrough.

3S. A combination as defined in claim 33 including valve means in saidsupply conduit means intermediate said location in said pump, said valvemeans including fixed area orice means to permit fuel to be suppliedcontinuously therethrough and variable area passage means for providingadditional fuel fiow through said valve means in response topredetermined engine operating conditions.

36. A fuel injection system for supplying fuel to an engine, said fuelinjection system comprising:

nozzle means for injecting fuel into the engine;

supply conduit means for supplying -fuel to the nozzle means;

a fuel pump for pumping fuel through said supply conduit means to thenozzle means;

a metering valve for controlling the amount of fuel pumped through saidsupply conduit means to said nozzle means; said metering valve having afirst position in which a first amount of fuel can flow therethrough tosaid nozzle means and a second position in which a substnatially lesseramount of fuel can flow through the metering valve to said nozzle means;

primary bypass passage means for bypassing some of the fuel pumped bysaid fuel pump;

Y adjustable means in said primary bypass passage means for varying therate of fuel ow therethrough; secondary bypass passage means forbypassing some of the fuel pumped by said fuel pump; and

valve means for automatically permitting a greater quantity of fuel tobe bypassed through the secondary bypass when the metering valve is inthe second position than when the metering valve is in the firstposition.

37. A fuel injection system as defined in claim 36 wherein saidadjustable means includes at least first and Second fluid passages ofdifferent cross sectional areas and means for selectively causing thefuel in the primary bypass passage means to flow through said first andsecond uid passages, respectively, to thereby vary the fiow rate throughthe primary bypass passage means.

38. A fuel injection system as defined in claim 36 including a valvemember in said secondary bypass passage means and means for biasing saidvalve member to a closed position `whereby said secondary bypass passagemeans remains closed until sufficient fuel pressure is present to opensaid valve member against the force of said biasing means.

39. A combination as defined to claim 27 wherein a supercharger isprovided to supply air to the engine and said valve means is responsiveto said predetermined pressure condition to open at approximately theinstant that there is some pressure increase in the manifold as a resultof supercharger operation.

40. A combination defined in claim 29 wherein said valve means ispositioned in said supply conduit means intermediate the metering valveand the fuel pump.

41. A fuel injection system for supplying fuel to an engine comprising:

a nozzle means for injecting fuel into the engine;

supply conduit means for supplying fuel to the nozzle means;

4a fuel pump for pumping fuel through said supply conduit means and thenozzle means to the engine;

bypass means for bypassing some of the fuel pumped by said pump;

a metering valve for controlling the amount of fuel pumped through saidsupply conduit means to said nozzle means, said metering valve beingmovable between a first position in which substantial quantity of fuelcan pass therethrough to the engine and a second position in which asubstantially lesser quantity of fuel can pass therethrough to theengine;

means for directing more fuel through said bypass means when themetering valve is in said second position thann when said metering valveis ,in said first position;

valve means in said supply conduit means for providing .additionalcontrol over the fuel ow to' said nozzle means by permitting greaterquantities of fuel to fiow therethrough in response to an increase inthe pressure of the fuel supplied by Said pump, at least some of thefuel passing through the valve means also passing through the meteringvalve; and

means dening a fuel flow passage for supplying fuel from the pump tosaid nozzle means independently of said valve means.

42. A fuel injection system as defined in claim 41 wherein said bypassmeans includes a secondary bypass,

said fuel injection system also including ya primary bypass having aplurality of individual bypass passages therein, each of which has amaximum ow rate and means for selectively allowing fuel to fiow throughone of said passages while blocking fuel ow from said conduit meansthrough the other of said passages whereby the amount of fuel returningthrough said primary bypass can be rapidly changed.

43. A fuel injection system as defined in claim 41 including highspeedcut-off valve means responsive to the engine exceeding approximately thespeed at which horsepower is maximum for causing at least some of theexcess fuel to return through said feedback conduit means at a ratewhich increases with respect to pump delivery rate.

44. A combination as defined in claim 3 including economizer valve meansin said conduit means responsive to fuel pressure in said conduit meanslfor providing additional control over the fuel flowing through saidconduit means, at least some of the fuel flowing through said-economizervalve means also owing through said metering valve means.

45. A combination as defined in claim 10 including valve means in saidconduit means responsive to a predetermined pressure condition in saidconduit means for opening to permit said fuel pump to supply fuel tosaid nozzle through said supply conduit means and means defining a fuelflow passage for supplying fuel from the fuel pump to said inletmanifold independently of said valve means and said predeterminedpressure condition whereby the opening of said valve means providesadditional fuel to the inlet manifold to thereby tailor the fuel flow tothe inlet manifold.

46. A combination as defined in claim 12 including pressure responsivevalve means in said conduit means downstream of said fuel pump forcontrolling the rateV of fuel flow therethrough in response to fuelpressure in said conduit means.

47. A combination as defined in claim 33 wherein said accelerationchamber is a closed and substantially fixed volume chamber.

48. A fuel injection system for supplying fuel to an engine comprising:

supply conduit means for supplying fuel to the engine;

a fuel pump for pumping fuel through said supply conduit means to theengine;

a metering valve for controlling the amount of fuel pumped through saidsupply conduit means to the engine;

primary bypass passage means for bypassing some of the fuel pumped bysaid fuel pump;

adjustable means in said primary bypass passage means for varying therate of fuel fiow therethrough;

secondary bypass passage means for bypassing some of the fuel pumped bysaid fuel pump; and

valve means for controlling the amount of fuel bypassed through saidsecondary bypass passage means, said valve means including a valvehousing -for receiving at least some of the fuel pumped by said fuelpump and a movable valve element in said housing, said valve elementhaving .a passageway 60 therein movable with said valve element toselectively provide communication between the fuel pumped to saidhousing and the secondary bypass passage means downstream of said valveelement whereby said valve element controls fuel ow through saidsecondary bypass passage means.

49. A fuel injection system as defined in claim 43 wherein said valveelement is rotatable, said metering valve has a rst position in which afirst amount of fuel can flow therethrough to the engine and a secondposition in which a substantially lesser amount of fuel can flow throughthe metering valve to the engine, and said adjustable means includes atleast first and second fluid passages of different cross sectional areasand means for selectively causing the -fuel in the primary bypasspassage means to liow through said first and second fluid passages,respectively, to thereby vary the liow rate through the primary bypasspassage means.

S0. A fuel injection system for supplying fuel to an engine comprising:

supply conduit :means for supplying fuel to the engine:

a fuel pump forpumping fuel through said supply conduit means to theengine;

a metering valve for controlling the amonut of fuel pumped through saidsupply conduit means to the engine, said metering valve having a fullopen position in which maximum fuel flow therethrough to the engine mayoccurv and a second position in which a substantially lesser amount offuel can flow through the metering valve to the engine;

secondary bypass passage means for bypassing some of the fuel pumped bysaid fuel pump; and

valve means for controlling the amount of fuel bypassed through saidsecondary bypass passage means, said valve means including a valvehousing for receiving at least some of the fuel pumped by said fuel pumpand a movable valve element in Said housing, said valve element having apassageway therein movable with said valve element to selectivelyprovide communication between the fuel pumped to said housing and thesecondary bypass passage means downstream of said valve element wherebysaid valve element controls fuel flow through said secondary bypasspassage Ine-ans.

51. A fuel injection system as defined in claim 5u wherein said valveelement is rotatable relative to said housing, said fuel injectionsystem also including a valve member in said secondary bypass passagemeans and means for biasing said valve member to a closed positionwhereby said secondary bypass passage means remains closed untilsuflicient fuel pressure is present to open said 50 valve member againstthe force of said biasing means.

References Cited UNITED STATES PATENTS 2,869,527 1/1959 Groves 123-1192,880,714 4/1959 Clark 123-l40.3 2,957,464 10/1960 Dolza 123-1193,079,904 3/1963 Scibbe et al. l23-l39 3,187,732 6/1965 Orner 123-1193,386,428 6/1968 Slabbey et al. 12S-139.18

LAURENCE M. GOODRIDGE, Primary Examiner U.S. Cl. X.R. 123-119, 140

